No, I probably would not correct an airline that had made a mistake on crediting me with too many miles. On the converse, I generally do not call or write when I am shorted miles either. I.e., it is just not worth fretting over that 526 mile flight or the fact that Budget Auto Rental did not credit a half segment to SWA.

Now, on those occasions where the ante is larger (e.g., 6,000 miles at one time) I have written and received credit.